Film base material

ABSTRACT

The present invention relates to film base material. A film of synthetic linear polyester has superimposed thereon a phenoxy resin of the formula ##SPC1## 
     Wherein each of R 1  to R 7  is a hydrogen atom or a lower alkyl or cyclohexyl group, R 8  is a hydrogen atom or an acyl radical of the formula ##EQU1## wherein m is 0 to 6, at least one of X, Y and Z is a chlorine or bromine atom or a cyano group, the other of X, Y and Z are each hydrogen atoms or bromine or chlorine atoms, n is at least 50 and from 50 to 100 % of the R 8  groups are a said acyl residue. An improved adhesion between the film base material of this composition and a hydrophilic layer coated thereon is achieved.

It is known that self-supporting films formed of synthetic linearpolyesters, particularly of the polyesters formed by reaction ofethylene glycol and terephthalic acid, may be prepared with mechanicaland physical and chemical properties which, for example, render themvery suitable indeed as base materials on which may be coated silverhalide photographic emulsion layers for the production of photographicfilm materials.

However, since such base materials are inherently highly hydrophobic andthe usual gelatino silver halide emulsions are highly hydrophilic, thereis great difficulty in securing adequate anchorage between the base filmand the emulsion layer, especially bearing in mind that the anchoragemust remain firm throughout the processing sequence of the finalphotographic film.

It is known to deal with such a difficulty by the provision of ananchoring layer or layers (so-called "subbing" layers) between the filmand the emulsion layer, but the materials hitherto suggested for thispurpose in connection with other film bases have not always provedentirely satisfactory when applied to film base of synthetic linearpolyesters of highly hydrophobic character.

Therefore according to the present invention there is provided film basematerial comprising a film of synthetic linear polyester of highlyhydrophobic character having superimposed thereon adherent to said filma layer which comprises a phenoxy resin which has been partiallyesterfied or completely esterified with a carboxylic acid, the phenoxyresin having the formula ##SPC2##

Wherein each of R₁ - R₇ is a hydrogen atom or a lower alkyl orcyclohexyl group, R₈ is a hydrogen atom or represents the acyl residueof the formula ##STR1## wherein m is 0 to 6, at least one of X, Y and Zis a chlorine or bromine atom or a cyano group, the others of X, Y and Zare each hydrogen atoms or chlorine or bromine atoms, n is at least 50and from 50 to 100% or more narrowly, from 70 to 100% of the R₈ groupsare a said acyl residue.

By lower alkyl group is meant an alkyl group having from 1 to 6 carbonatoms.

Preferably R₁ and R₂ in formula I are each methyl groups.

Preferably not more than two of R₃ - R₇ are lower alkyl group, theremainder being hydrogen atoms. Most preferably each of R₃ - R₇ arehydrogen atoms.

Preferably in formula II m is 0, 1 or 2. Preferably also in formula IIonly one of X, Y and Z is a chlorine atom.

In formula I it is preferred that n is 80-110 and most preferably about100. When n is greatly in excess of 100 it is difficult to coat theresins on to the film base because they are not easy to dissolve to formcoating mixtures.

In order to prepare the film base material of the present invention itis necessary to treat the film of synthetic linear polyester before theresin layer is coated thereon.

Therefore according to another aspect of the present invention there isprovided a process for the production of film base material whichcomprises treating at least one side of a film of synthetic linearpolyester of highly hydrophobic character to enable a resin layer toadhere thereto and then coating on to the treated sides or sides anorganic solvent solution of a phenoxy resin of formula I.

Suitable organic solvents in which to dissolve the phenoxy resin offormula I are methyl ethyl ketone, dioxan and acetone or mixturesthereof.

Preferably the treatment of the side of the film of synthetic linearpolyester which enables a resin layer to adhere thereto is to coat on tothe side of the polyester film an organic solvent solution of a phenolicadhesion promoting agent and then to remove the solvent, preferably byevaporation.

Synthetic organic solvents in which to dissolve the phenolic adhesionpromoting agents are methanol, ethanol, methyl ethyl ketone, acetone anddioxan or mixtures thereof.

By "phenolic adhesion promoting agent" is meant a phenol-based ornaphthol-based compound which is capable of acting on the polyester filmbase so as to render its surface more receptive to an applied layer.Examples of such compounds are m-cresol, o-cresol, resorcinol, orcinol,catechol, pyrogallol, 1-naphthol, each of which compounds may besubstituted with one or more chloro-, fluoro- or nitro-substituents, andphenol substituted with one or more chloro-, fluoro- ornitro-substituents. The action of the adhesion promoting agent on thepolyester film base is thought to be a swelling action and polyestersurfaces so treated are receptive to certain polymeric subbing layersbut not to hydrophilic layers, for example a gelatin or polyvinylalcohol.

Alternatively the film of polyester may be treated by a physical method,for example corona discharge treatment, which renders the surfacecapable of accepting a resin layer as described in British patentspecifications Nos. 1,262,127, 1,267,215 and 1,286,457.

The film base material of the present invention is able to accept ahydrophilic layer adherent thereto, for example a gelatin based layer, apolyvinyl alcohol layer or polyvinyl acetal layer.

The gelatin based layer may be a gelatino silver halide emulsion layerbut usually when the process of the present invention is employed toprepare film base material for use in the production of photographicgelatino silver halide material an intermediate gelatin layer isprovided between the phenoxy resin layer of formula I and the silverhalide emulsion layer. Such an intermediate layer is used in theexamples which follow.

In order to obtain improved adhesion between the film material of thepresent invention and a hydrophilic layer adherent thereto it ispreferred that after the hydrophilic layer has been coated thereon thematerial is incubated or stored at an elevated temperature for one ortwo days.

Alternatively the hydrophilic layer when coated on to the film basematerial may have incorporated therein an alkaline substance, mostpreferably a volatile alkaline substance, for example ammonia. In thisembodiment the hydrophilic layer adheres very tightly to the film basematerial without the need to incubate the material.

When the hydrophilic layer to be applied to the film base material asprepared by the process of the present invention is polyvinyl alcohol orpolyvinyl acetal such a hydrophilic layer may comprise a light-sensitivediazonium salt to produce a diazotype material. Alternatively afterpolyvinyl alcohol or polyvinyl acetal layer has been coated on to thefilm base material as prepared by the process of the present inventionthe polyvinyl alcohol or polyvinyl acetal may have incorporated thereinor be coated with a light-sensitive diazonium salt to produce adiazotype material.

A commercially available phenoxy resin of formula I but wherein R₈ isentirely hydrogen is marketed by Union Carbide as P K D A phenoxy resin.

This resin can be converted to the ester of formula I by reacting anorganic solvent solution of the phenoxy resin with an acyl chloride ofthe formula ##STR2## where m, X, Y and Z have the above meanings in thepresence of pyridine at an elevated temperature.

Suitable acyl chlorides are chloroacetyl chloride, chlorobutyrylchloride, chloropropionyl chloride, cyanoacetyl chloride, cyanobutyrylchloride, trichloroacetyl chloride and bromoacetyl chloride.

PREPARATION

To a solution of 25 g of P K D A 8500 phenoxy resin, which is a compoundof formula I wherein R₁ and R₂ are methyl groups and R₃ - R₈ arehydrogen atoms, in 200 ml or dry dioxan there was added 18 ml ofpyridine. To this solution was then added slowly and with stirring 10 mlof chloroacetyl chloride. The mixture was then warmed. When the reactionwas complete the solution was poured into aqueous propan-2-ol toprecipitate the esterified resin. After washing and drying theesterified resin was purified by dissolving it in methyl ethyl ketoneand reprecipitating it with aqueous propan-2-ol. A 99% esterified resinwas obtained.

The chlorobutyryl and chloropropionyl esters of a resin of formula Iwere prepared in a similar manner using chlorobutyryl chloride orchloropropionyl chloride instead of chloroacetyl chloride. In each casethe resin was 75% esterified.

EXAMPLE I

The following coatings were applied sequentially to biaxially orientedfilm based on the synthetic linear polyester obtained from ethyleneglycol and terephthalic acid which is highly hydrophobic.

First coating

    ______________________________________                                        p - Chloro-m-cresol        2 g                                                Methanol                  100 ml                                              ______________________________________                                    

dried 2 minutes at 70°C.

Second coating

    ______________________________________                                        Monochloroacetate ester                                                       (approximately 99%                                                            esterified) of the                                                            phenoxy resin PKDA 8500                                                       as previously prepared.    2 g                                                Methyl ethyl ketone       100 ml                                              ______________________________________                                    

dried 5 minutes at room temperature.

Third coating

    ______________________________________                                        Gelatin                   6.8 g                                               Phenol                    0.38 g                                              Wetting agents            0.36 g                                              Water to                  410 ml                                              pH adjusted to 10                                                             by the addition of                                                            ammonia (0.920)                                                               ______________________________________                                    

air dried for 5 minutes followed by 15 minutes at 105°C.

Subsequentially there was applied to the gelatin coating on the subbedfilm base a layer of conventional photographic gelatino silver halideemulsion. It was found that the layers were strongly adherent to oneanother and to the film support so that the final photographic filmcould be processed without danger of separation of the layers orfrilling.

EXAMPLE II

The following coatings were applied sequentially to biaxially orientedfilm based on the synthetic linear polyester obtained from ethyleneglycol and terephthalic acid which is highly hydrophobic.

First coating

    ______________________________________                                        p - Chloro-m-cresol        2 g                                                Methanol                  100 ml                                              ______________________________________                                    

dried 2 minutes at 70° C.

Second coating

    ______________________________________                                        Monochlorobutyrate                                                            ester (75% esterified)                                                        of the phenoxy resin of                                                       PKDA 8500 as previously                                                       prepared.                  2 g                                                Methyl ethyl ketone       100 ml                                              ______________________________________                                    

dried 5 minutes at room temperature.

Third coating

    ______________________________________                                        De-ashed gelatin        1.68    g                                             Water                   8.0     ml                                            Ammonia (0.920)         1.2     ml                                            Methanol                90.7    ml                                            Ethyl lactate           1.09    ml                                            Formalin, 30% by weight                                                       aqueous solution.       0.07    ml                                            ______________________________________                                    

air dried for 5 minutes, then heated to 105°C for 15 minutes to removethe methanol.

Subsequentially there was applied to the gelatin coating on the subbedfilm base a layer of a conventional photographic gelatino silver halideemulsion. It was found that the layers were strongly adherent to oneanother and to the film support so that the final photographic filmcould be processed without danger of separation of the layers orfrilling.

We claim:
 1. Film base material comprising a film of synthetic linearpolyester of hydrophobic character having superimposed thereon adherentto at least one entire side of said film a layer which comprises aphenoxy resin of the formula ##SPC3##wherein each of R₁ through R₇ ishydrogen, lower alkyl or cyclohexyl, from 50 to 100% of the R₈ groups inthe phenoxy resin represent the acyl radical of the formula##EQU2##wherein m is 0 or an integer from 1 to 6, at least one of X, Yand Z is chlorine, bromine or cyano, and the other of X, Y and Z areeach hydrogen, bromine or chlorine, any balance of the R₈ groups in thephenoxy resin being hydrogen, and n is at least
 50. 2. Film basematerial as claimed in claim 1 wherein the phenoxy resin is of theformula ##SPC4##wherein from 50 to 100% of the R₈ groups in the phenoxyresin represent the acyl radical of the formula ##EQU3##wherein mrepresents 0 or an integer from 1 to 6, at least one of X, Y and Z ischlorine, bromine or cyano, and the other of X, Y and Z are eachhydrogen, bromine or chlorine, any balance of the R₈ groups in thephenoxy resin being hydrogen, and n is at least
 50. 3. Film basematerial as claimed in claim 2 wherein the phenoxy resin is of theformula ##SPC5##wherein n₁ is 80 to 110 and from 70 to 100% of the R₈groups in the phenoxy resin represent the acyl radical of the formula##STR3##wherein m₁ is 0, 1 or 2 and U represents a radical selected fromthe group consisting of radicals of the formulae ##STR4##any balance ofthe R₈ groups in the phenoxy resin being hydrogen.
 4. Film base materialas claimed in claim 2 wherein the phenoxy resin is of the formula##SPC6##wherein n₁ is 80 to 110 and from 70 to 100% of the R₈ groups inthe phenoxy resin represent the acyl radical of the formula##STR5##wherein m₁ is 0, 1 or 2, any balance of the R₈ groups in thephenoxy resin being hydrogen.
 5. Film base material as claimed in claim2 wherein the phenoxy resin is of the formula ##SPC7##wherein R₈satisfies the requirements given in claim 11 and n₁ is
 6. Film basematerial as claimed in claim 2 which further comprises a gelatin basedlayer coated thereon.